In recent years, the so-called multi flow type heat exchangers have been widely used as, for example, car air-conditioning condensers. In some condensers, as shown in FIG. 4A, a header 100 having a round cross-sectional shape is employed so as to withstand the high pressure of the refrigerant passing through the condenser. On the other hand, as shown in FIG. 4B, a joined type header made by coupling a pair of header halves 102 and 103 is also widely employed.
By the way, since a header is a portion that does not contribute to a heat exchange and constitutes the so-called dead space, it is desirable to make the header capacity as small as possible from the viewpoint of heat exchange efficiency.
In the former header 100 having a circular cross-sectional shape, although the header 100 is excellent in pressure resistance, it is required to have a diameter large enough to allow an insertion of an end portion of the tube 101. This inevitably increases the maximum diameter of the header in the longitudinal direction of the tube 101, resulting in an increased inner capacity of the header 100, or an enlarged dead space that does not contribute to a heat exchange.
On the other hand, in the latter joined type header, since the header has a generally flattened circular cross-sectional shape, it is possible to reduce the Inner capacity of the header, which enables to decrease the dead space to some extent. However, in order to secure enough pressure resistance, it is required to increase the thickness of the inner header half 102 through which the tubes 101 are inserted, which causes an increased header weight. Thus, it was difficult to reduce the weight of the header.
The object of the present invention is to provide a heat exchanger that can reduce the inner capacity of the header while securing enough pressure resistance and lightweight.